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Posted to issues@spark.apache.org by "Wang Cheng (JIRA)" <ji...@apache.org> on 2018/01/08 07:17:00 UTC
[jira] [Updated] (SPARK-22988) Why does dataset's unpersist clear all the caches have the same logical plan?

     [ https://issues.apache.org/jira/browse/SPARK-22988?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Wang Cheng updated SPARK-22988:
-------------------------------
    Description: 
When I do followings:
dataset A = some dataset
A.persist

dataset B = A.doSomthing
dataset C = A.doSomthing

C.persist
A.unpersist

I found C's cache is removed too, since following code:
def uncacheQuery(spark: SparkSession, plan: LogicalPlan, blocking: Boolean): Unit = writeLock {
    val it = cachedData.iterator()
    while (it.hasNext) {
      val cd = it.next()
      if (cd.plan.find(_.sameResult(plan)).isDefined) {
        cd.cachedRepresentation.cachedColumnBuffers.unpersist(blocking)
        it.remove()
      }
    }
  }

It removes the data caches contain the some logical plan, should it only remove the cache whose dataset calls unpersist method? 

  was:
When I do followings:
dataset A = some dataset
A.persist

dataset B = A.doSomthing
dataset C = A.doSomthing

C.persist
A.unpersist

I found C's cache is removed too, since following code:
def uncacheQuery(spark: SparkSession, plan: LogicalPlan, blocking: Boolean): Unit = writeLock {
    val it = cachedData.iterator()
    while (it.hasNext) {
      val cd = it.next()
      if (cd.plan.find(_.sameResult(plan)).isDefined) {
        cd.cachedRepresentation.cachedColumnBuffers.unpersist(blocking)
        it.remove()
      }
    }
  }

It removes the data caches contains the some logical plan, should it only remove the cache whose dataset calls unpersist method? 


> Why does dataset's unpersist clear all the caches have the same logical plan?
> -----------------------------------------------------------------------------
>
>                 Key: SPARK-22988
>                 URL: https://issues.apache.org/jira/browse/SPARK-22988
>             Project: Spark
>          Issue Type: Question
>          Components: Spark Core
>    Affects Versions: 2.1.1
>            Reporter: Wang Cheng
>            Priority: Minor
>
> When I do followings:
> dataset A = some dataset
> A.persist
> dataset B = A.doSomthing
> dataset C = A.doSomthing
> C.persist
> A.unpersist
> I found C's cache is removed too, since following code:
> def uncacheQuery(spark: SparkSession, plan: LogicalPlan, blocking: Boolean): Unit = writeLock {
>     val it = cachedData.iterator()
>     while (it.hasNext) {
>       val cd = it.next()
>       if (cd.plan.find(_.sameResult(plan)).isDefined) {
>         cd.cachedRepresentation.cachedColumnBuffers.unpersist(blocking)
>         it.remove()
>       }
>     }
>   }
> It removes the data caches contain the some logical plan, should it only remove the cache whose dataset calls unpersist method? 



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